---
title: size
framework: IOKit
role: symbol
role_heading: Instance Property
platforms: [iOS 18.4+, iPadOS 18.4+, Mac Catalyst 13.0+, macOS 10.6+, visionOS 2.4+]
path: iokit/osnotificationheader64/1455592-size
---

# size

## Declaration

```swift
var size: mach_msg_size_t
```